    <?php
    class Mage_Adminhtml_Model_System_Config_Source_Shipping_Flatrateuk
    {
        public function toOptionArray()
        {
            return array(
                array('value'=>'', 'label'=> Mage::helper('adminhtml')->__('None')),
                array('value'=>'O', 'label'=>Mage::helper('adminhtml')->__('Per Order')),
                array('value'=>'I', 'label'=>Mage::helper('adminhtml')->__('Per Item')),
            );
        }
    }
    ?>